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Protesters gathered outside the Chinese embassy in west London today to callfor a ban on the country's booming trade in ivory from elephant tusks.

Chinese demand for ivory is claimed to be driving the slaughter ofan estimated 40,000 African elephants every year.

With the animals in danger of extinction, wildlife charities are asking China to ban the ivory trade, destroy all its ivory stocks and close ivory carving factories.

Ornaments made from ivory are a traditional symbol of wealth and status in China.

"It's no secret that China holds the key to saving the planet's elephants, or making them extinct in the very near future.

"Although it was very encouraging to see China destroy six tonnes of seized ivory in the early part of this year, it's time now for China to take a much bigger leap forward and send a clear statement to the world - by banning the sale of ivory once and for all."

As Thailand bows to international pressure by vowing to bring an end to its legal internal ivory trade, here in the UK the criminal trade appears to be taking place right under the nose of the authorities.

Heathrow Airport is emerging as one of the fastest-growing transit points for ivory from Africa to the Far East. Our Special Correspondent Rageh Omaar has been investigating. You may find some of the images disturbing.